That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

I caution frog keepers against the all-too-common “cricket and mealworm only” diet.  Today we’ll cover additional means of providing amphibians a varied diet that will promote longevity and breeding.  The following information applies to the care of American Bullfrogs, White’s Treefrogs, Budgett’s Frogs, most toads and many similar species.  Please see my other Amphibian Care Articles for details concerning Poison Frogs, Mantellas, African Clawed Frogs, Horned Frogs and others requiring specialized diets, or write in with your questions. 

Wild-Caught Invertebrates

There is very little in the way of live invertebrates that hungry frogs refuse – I provide moths, beetles, sowbugs, millipedes, dragonfly larvae, grubs, millipedes, grasshoppers, tree crickets, field crickets, harvestmen, caterpillars and a variety of other easily-collected species.

Avoid using “hairy” caterpillars, spiders and other invertebrates that are able to bite or sting – a good invertebrate field guide should be part of every herpers “tool chest”.  Brightly-colored insects are often toxic, as are fireflies; do not collect during times when your area is being sprayed for mosquito control.

I rely heavily upon earthworms in both winter and summer, buying or collecting them, and usually try to keep a colony going in my basement as well.

Traps and Canned Insects

The Zoo Med Bug Napper simplifies the collecting of moths and other flying insects; please see the articles mentioned in Part I for information on other collecting techniques.

Canned Insects such as grasshoppers, snails and silkworms are readily accepted from Feeding Tongs by many frogs, and are an important means of providing dietary variety when wild-caught insects are not available.

Calcium: Fish and Mice

A minnow or shiner each 7-10 days helps ensure adequate calcium intake for frogs the size of an adult Leopard Frog or larger.

A diet rich in pink or adult mice will cause most frogs to suffer eye, kidney and liver problems.  While these aggressive predators certainly take the occasional rodent in the wild, research has shown that insects and other invertebrates form the vast majority of their natural diet.

American Bullfrogs seem to do well with a pink mouse every month or so, but do not offer adult mice – amphibians swallow their food alive, and are often injured by a mouse’s sharp teeth.  Hair also leads to potentially fatal impactions.

Commercially-Grown Invertebrates

During the colder months, or at other times when wild-caught insects are unavailable, the main portion of the diet should not be crickets, but rather a mix of earthworms (these can be used as the bulk of most species’ diets), roaches, crickets, and waxworms.  Silkworms and tomato hornworms, available via internet dealers, should be offered from time to time.

I use mealworms and super mealworms sparingly, and usually select only newly-molted (white) individuals.  I have found crayfishes to be an important food item for a wide variety of frogs.  I remove their claws, just to be on the safe side.

You should allow insects purchased as frog food to consume a healthy diet for several days, in order to increase their nutritional value; please see the articles referenced in Part I for details.

I powder most store-bought insects with supplements, alternating among Reptivite with D3,  ReptiCalcium and Reptocal.  I do not use supplements when feeding wild-caught invertebrates.

Further Reading

Raising Earthworms

Those of us who keep and breed small aquatic amphibians usually have a difficult time providing our pets with dietary variety.  This is especially true as regards salamander larvae and other creatures that usually accept only live foods.  In most cases, such animals must make do with the pet trade staples, Brine Shrimp and Blackworms.  Today I’d like to introduce a useful aquatic food item that is popular with aquarists but often over-looked by herp keepers – the Bloodworm (Chironomus spp.).

Natural History

Bloodworms resemble, but are unrelated to, aquatic worms.  Rather, they are the larvae of tiny flying insects known as Midges (often called “Gnats”) of the Family Chironomidae.  They have long been sold in stores specializing in tropical fishes, and can also be ordered from internet dealers.  Read More »

Springtails are minute, primitive, wingless insects classified in the Order Collembola.  Over 6,000 species are found in most temperate and tropical habitats, where they figure importantly in the diets of Poison Frogs (Dendrobates, Phyllobates, Oophaga), small salamanders and newly metamorphosed amphibians of many kinds. Please see Part I of this article for information on procuring Springtails and their role in helping to save the nearly extinct Kihansi Spray Toad (Nectophrynoides asperginis). Read More »

The diets of captive Poison Frogs (Dendrobates, Phyllobates, Oophaga), Mantellas, small salamanders (i.e. Red-Backed Salamanders) and tiny, newly-transformed amphibians are usually limited to the two readily available foods of appropriate size – pinhead crickets and fruit flies.  The minute, wingless insects known as Springtails (Order Collembola) are easy to procure and rear, and offer a convenient means of increasing dietary variety for small amphibians.

Natural Diets of Smaller Amphibians

Most small terrestrial frogs and salamanders forage among leaf litter, which is invariably inhabited by thousands of species of tiny invertebrates (surprisingly, the weight of invertebrates in most habitats exceeds that of all vertebrates combined!).  It seems certain that these amphibians consume an extremely varied diet in the wild, and that typical captive diets do not meet their nutritional needs.

Aphids (1/8-inch-long green or red insects found in colonies on plant stems) are an option, but these are becoming scarce in many areas and, with their complicated life history (involving sex-switching and other unique twists), are difficult to maintain long-term.  One can also collect ants, tiny beetles and other leaf litter invertebrates (please see article below), but of these only Springtails can be easily bred in large numbers.

Problematical Captives

Some amphibians are so small that even pinhead crickets prove too large a meal.  I’ve run into this situation with Kihansi Spray Toads (Nectophrynoides asperginis), which are a mere ¾ inch long when full grown.  These toads, now likely extinct in the wild, give birth to fully formed toadlets that are so small as to be barely visible.  A steady supply of Springtails was essential to the successful rearing of these Tanzanian natives, the last of their kind on earth.  Folks breeding other tiny amphibians, such as Strawberry Poison Frogs (Oophaga pumilio), will also find Springtail colonies an invaluable resource.

Procuring Springtails

With over 6,000 species identified thus far, Springtails are common in most temperate and tropical habitats.  They usually appear as tiny white “dots” jumping about below fallen leaves.  You can start a colony by scooping them up in the leaf litter or by purchasing any of the several species available through commercial suppliers.  Most breed well in captivity and can build up enormous populations under favorable conditions – please see Part II of this article for details.

Further Reading

Whenever possible, the diets of smaller amphibians should be supplemented with wild-caught invertebrates.  Please see Collecting Leaf Litter Invertebrates for some useful techniques.

Strawberry Poison Frog image referenced from wikipedia and originally posted by Encarna Sáez Goñalons & Víctor Martínez Moll

Springtail image referenced from wikipedia and originally posted by Mvuijlst

Please see Part I of this article for a general discussion regarding the collection of insects and other invertebrates and their use in the diets of captive reptiles, amphibians, birds, invertebrates and fishes. Today I’d like to focus on some areas of special concern.

Toxic and Biting/Stinging Invertebrates

While not involving pesticides per se, for your own safety and that of your collection it is imperative that you learn to identify the toxic or otherwise dangerous invertebrates that you may encounter while collecting. A good field guide (i.e. Audubon, Golden Guide or Peterson series) is indispensable in this regard. Be sure to handle unfamiliar species with plastic tongs.

Please bear in mind that even relatively mild bee venom can cause fatalities in allergic people. And while less than 1% of the world’s 40,000+ species of spiders are considered dangerously venomous to us, a number readily bite both people and animals in self defense. It is best, therefore, to avoid them…the Thin-legged Harvestman or “daddy long-legs”, which are not spiders, are safe to use. Steer clear also of bees, wasps, large ants, stag beetles and others well-equipped to defend themselves.

Bright colors often indicate that an animal is toxic or bad-tasting; ladybugs, fireflies, milkweed bugs and a great many others fall into this category. Unless you are sure of an insect’s identity, the safest course of action is to avoid brightly-colored species.

Native vs. Non-Native Prey Species

In many cases, predators avoid dangerous prey animals that occur naturally within their ranges; this can spare both pet and pet-keeper a good deal of grief!  However, dangerous non-native prey animals may be attacked with abandon if the hunter has no “frame of reference”, so use extra caution in such cases.

I have, for example, housed highly-toxic Marine Toads with Green Anacondas for decades without incident, despite the fact that anacondas consume non-toxic frogs readily. However, Australian monitors and snakes, which have no instinctive or learned toad avoidance behavior, eagerly consume the Marine Toads that have been introduced there, often with fatal results.

Earthworms

Earthworms are one of the most nutritious live foods available. There are, however, situations that warrant precautions.

Earthworms are unique in consuming dirt as they tunnel, and in doing so may concentrate toxins present there. To my knowledge, the only problem that has arisen thus far has involved worms that dwell along golf courses, which are subjected to unusually high degrees of pesticide application. Please see my article Raising Earthworms for details concerning striped skunks and earthworms in NY.

West Nile Control and Related Programs

Avoid collecting invertebrates for 1 week after an area has been sprayed as part of West Nile eradication efforts, and steer clear of farms where pesticides are known to be applied regularly. Avoid also local insects that are considered to be agricultural pests, as they are likely the subject of control measures (this may apply to aphids, caterpillars, Japanese Beetles, etc.).

Enjoy

Despite the precautions that must be taken, invertebrate collecting is a fascinating and thoroughly enjoyable endeavor. Don’t forget to examine your catch closely…several years ago a new species of centipede was uncovered in NYC’s Central Park, on ground trod daily by thousands of people. Like me, you just may wind up keeping some of your discoveries in captivity for their own sake!

Further Reading

For a very interesting account of how toads learn to avoid stinging insects, please see my article Amphibian Learning Abilities.

Please write in with your questions and comments.

Black Widow image referenced from wikipedia and originally posted by Trachemys.

Milkweed Bugs image referenced from wikipedia and originally posted by Greg5030.